Diaphragm



March 31, 1931. w p LA RUE 1,798,638

DIAPHRAGM Filed Aug. 21, 1926 4 Sheets-Sheet l a MAMA E March 31, 1931. w. D. LA RUE March 31, 1931. w. D. LA RUE Filed Aug. 21, 1926 4 Sheets-Sheet 3 March 31, 1931. w. D. LA RUE DIAPHRAGM Filed Aug. 21, 1926 4 Sheets-Sheet 4 g wmm WM A Am 3% m wkhdmm atto'lnut Patented Mar. 31, 1931 UNITED STATES WILLIAM D.

LA RUE, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO VICTOR TALK- ING MACHINE COMPANY, A CORPORATION OF NEW JERSEY DIAPHRAGM Application filed August 21, 1926. Serial No. 130,662.

This invention relates to diaphragms and particularly to diaphragms of conical construction and large area for use in acoustical instruments Without the necessity of a horn t or other sound amplifying device,

It has heretofore been proposed to provide a large diaphragm of pleated formation by reversely folding or flexing a long, rectangular strip of suitable material, joining the ends of the pleated strip and pressing it out until the pleats are radially disposed in substantially a single plane. A diaphragm of this character possesses certain advantages, because it may be made of relatively large size, on the order of eight to ten inches in diameter, for placing a relatively large volume of air into vibration to produce sounds of the desired volume without the necessity for a horn or other amplifying mechanism.

A diaphragm of this construction, although possessed of considerable rigidity or resistance to transverse fiexure, still possesses considerable flexibility throughout its area. Experience has demonstrated that it is desirable, particularly in transmitting lower frequencies, for the diaphragm to be relatively stiff, so that its vibrations will partake more of the characterof a plunger or piston.

One object of this invention is to retain the 36 advantages of a pleated diaphragm as heretofore provided and at the same time to give greater stiffness to the diaphragm so that its vibrations will partake more of the characteristics of a piston or plunger.

Another object of this invention is to provide a diaphragm of the pleated type having a generally conical or frusto-conical form.

Another object of this invention is to provide a diaphragm which will. partake of the characteristics of a pleated diaphragm in the marginal portion and be without the concentration of mass or weight at the central portion of the diaphragm which is incident to a pleated diaphragm of conical conformation, as falls within the object above stated.

Another object of this invention is to provide a diaphragm which Will partake of the characteristics of a pleated diaphragm in its marginal portion and be relatively stiif and light in its central portion, so as to combine maximum rigidity with minimum Weight in a diaphragm adapted to vibrate after the manner of a. piston or plunger.

Another object of this invention is to provide a diaphragm of the pleated type embodying a portion having the form of a truncated cone and another portion constituting a closure for the small end of the conical portion.

Another object of this invention is to provide a diaphragm having a pleated portion and an unpleated portion.

Another object of this invention is to provide a diaphragm embodying a pleated truncated conical portion and an unpleated conical portion.

Another object of this invention is to provide a diaphragm having a truncated conical portion, whether pleated or not, and a central reentrant portion, whether pleated or not.

Another object of this invention is to provide a novel pleated diaphragm of generally conical or frusto-conical form in combination with novel means for supporting the same.

Referring to the accompanyin drawings illustrating several expressions 0 the inventive idea: 7

Figs. 1 and 2 are a plan View and a sectional side view respectively, illustrating one embodiment of the present invention;

Figs. 3 and 4 are a plan view and a sectional side view respectively of another form of the invention;

Figs. 5 and 6 are a plan view and asectional side view respectively'of still another embodiment of the inventive idea; and

Fig. 7 is a partial section and a partial elevation of still another embodiment of the present invention.

In Figs. 1 and 2, is shown a conical dia phragm 1 of pleated construction which embodies some of the broader features of the present invention. This diaphragm may be' Fill form and the pleats at one end cut off at a slight bevel or angle, which will vary with the angle of the cone to be formed, so that the fiat, folded body has a trapezoidal out line. A tube is now made of the pleated strip "by suitably joining the ends of the latter, as

by means of glue, being sure that the short creases, that are formed when the ends of the beveled ends2 of the pleats 3 being at the apex. Preferably, a conical center member 4 is placed in engagement with beveled ends 2 and secured thereto in any suitable manner, as by means of glue. The center member 4 constitutes means for connecting the diaphragm to its actuating device.

Novel means are provided for yieldingly securing the diaphragm to a rigid annular supporting member, not shown, of any suitable type. For this purpose, the ends of the pleats adjacent the base of the cone are shown as pressed outwardly at substantially right angles to the longitudinal axis of the cone, as indicated at 5 in Fig. 2,- and glued to the faceof this laterally extending. portion of the diaphragm are a plurality of thin arcuate strips 6 that are formed of some suitable flexible material, such as leather. If desired, openings? may be provided in the sectors to facilitate attachment of the supporting means to the usual rigid supporting ring or spider employed in diaphragms of this type.

In order to avoid the mass adjacent the apex of the cone-shaped diaphragm shown in Figs. 1 and 2, it may be desirable to form the diaphragm, of two portions, as illustrated in Figs. 3 and t. In this event, a strip of material is pleated as before but the length relative to the width of this strip is greater than in the form shown in Figs. 1 and 2. The pleated base portions is then formed into the frustum of a cone and provided. with a disklike central portion 9 of any suitable size, preferably formed of pleated material in the manner heretofore known in the art. The periphery of the disk-like central portion is suitably attached as by gluing to the inner end of the frusto-conical portion Sand a center member 10 provided with the usual flanges may be inserted in the center of the disk-like portion 9 to facilitate attachment of the diaphragm actuating means. It is also within the contemplation of this invention to make the central portion 9 of unpleated material.

The mass of material adjacent the center of the diaphragm, however, is preferably reduced, and greater stiifness at the center of the diaphragm attained, so as to obtain maximum rigidity with minimum mass, by making the diaphragm in the manner illustrated in Figs. 5 and 6. In this instance the diaphragm has a frusto-conical pleated por tion 11 which is formed in the manner described in connection with Figs. 4 and 5, and fixed in position in the circular opening at the central ends of the pleats is a smooth cone 12 which may be formed of paper, parchment or other suitable material, and which may have the same or a different conicity with respect to the marginal portion 11. The periphery of the cone 12, adjacent the base of the same, is suitably secured to the inner edges of the'beveled ends of the pleats of portion 11, as by means of glue. A center member 16 of suitable type is provided for facilitating the operative connection of the diaphragm with its actuating means.

In this embodiment of the invention the smooth conicalportion 12 provides maximum rigidity with minimum weight for a proj ected area of this size, and said conical por tion is surrounded by an annular portion formed of a plurality of elements or strips, each of which is under torsion and coacts with its adjacent strips on each side, which are at an angle thereto, so that there is thus secured a very rigid construction which may be composed of relatively thin material so that great stiffness is secured relative to the mass involved.

In the form shown in Fig. 7 the diaphragm iscomposed of a frusto conical portion 18, which is preferably of pleated formation as heretofore described, and. a central conical portion 14, which is preferably of smooth or unpleated formation and which may have the same or a different conicity as respects the peripheral portion 13. In this embodiment the central portion 14 is made reentrant with respect 'to' the peripheral portion 13 and thereby all of the advantagesinherent in the construction of Figs. 5 and 6 are obtained while the axial dimension of the diaphragm is materially decreasedand may, if desired, be equal to the axial height of the frustoconical portion. Said conical portion 14 is secured to the pleated peripheral portion 13 in any suitable way, being shown as provided with a flange 15 which is suitably secured, as by glue, to the inner ends of the pleats. In the structure shown said flange 15 is attached to the outer face of the pleats, but said flange may be attachedto the inner face of the pleats with equal facility if desired for smooth or unpleated formation and in this embodiment, as in other embodiments, it is not essential that the peripheral or the central portions of the diaphragm be of exactly conical shape, the term conical being used to include converging or substantially conical or frusto-conical formations although not strictly adhering to the geometrical definition of a cone.

It will therefore be seen that there is provided a diaphragm of relatively large size which may embody the advantages of a pleated diaphragm and at the same time has great stiffness so that its vibrations will partake more of the characteristics of a piston or plunger. In the preferred embodiment the diaphragm partakes of the characteristics of a pleated diaphragm in the marginal portion, and this Without the concentration of mass or weight at the central portion, so as to combine maximum rigidity with minimum weight in a diaphragm adapted to vibrate after the manner of a piston or plunger. Means have also been provided for supporting the diaphragm whereby a diaphragm of the type described may vibrate after the manner of a piston or plunger.

Additionally, while pleated diaphragms which are so constructed that the pleats lie in a plane are sensitive to changesin atmospheric conditions, since there is a tendency for the material to expand and cause the pleats to pucker, the cone-shaped diaphragm of the present invention is less adversely affected by atmospheric variations. Furthermore, the center of the diaphragm as constructed in conformity with the present invention may be brought nearer to the center or apex of the spider on which a diaphragm of this type is usually mounted, thereby enabling a shorter transmission to be employed between the diaphragm and its actuating means, or the full advantages of the conical formation may be secured with a minimum dimension in an axial direction, when the reentrant form is used.

It is to be understood that the term conical as employed herein includes not only a conical diaphragm, as well as a compound conical diaphragm, but also one which is frusto-conical in form. It is also to be understood that While it is preferred to make the marginal portion of the diaphragm of pleated form and the central portion of unpleated form, either or both portions may be made smooth or either or both portions may be made of pleated material. Thus a diaphragm having a smooth marginal portion of truncated form and a central reentrant portion of smooth form possesses marked advantages over conical diaphragms of large area heretofore proposed.

WVhile several forms of the inventive idea have been described with considrable particularity and illustrated in the accompanying drawings, it is to be expressly understood that the drawings are for purposes of illustration only, and are not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

This application is a continuation in part of my application Serial No. 98,880, filed March 31, 1926, for diaphragms.

What is claimed is 1. A pleated diaphragm of conical form.

2. A diaphragm formed in two portions, one of said portions being pleated and having a conical form.

3. A diaphragm of conical form comprising a pleated base portion and a center portion fixedly secured thereto.

4. A diaphragm comprising a pleated base portion having a truncated conical form, and a central portion fixedly secured to the small end of said conical portion.

5. A diaphragm comprising a pleated portion having the form of a frustum of a cone, and an unpleated portion of conical shape secured to the center thereof.

6. A diaphragm comprising a pleated portion having theformof a frustum of a cone, and an unpleated portion secured to the center thereof.

7. A diaphragm comprising a conical central portion and a pleated peripheral portion.

8. In combination, a relatively rigid diaphragm having radially extending pleats, and a plurality of flexible supporting elements secured to the peripherythereof.

9. In combination, a conical diaphragm having radially extending pleats, and yielding supporting means therefor, said means including a plurality of arcuate strips fixedly attached to the diaphragm adjacent the base of the same.

10. In combination, a relatively rigid dia phragm of large area having radially extending pleats, and means for mounting the diaphragm to permit oscillation of the same as a body.

11. In combination, a conical diaphragm of large area having radially extending pleats, and means for mounting said diaphragm, said means permitting oscillation of the diaphragm as a body.

12. A diaphragm having a conical portion surrounded by a portion formed of angularly-related flexed strips.

13. A diaphragm having a conical portion and attached to and surrounded by a portion formed of a plurality of flexed elements, each element held under a torsional stress due to its flexed condition and tending to return to an unflexed condition.

14. A conical diaphragm having a conical portion surrounded by a conical portion formed of a plurality of flexed elements, each of said elements being held distorted from a normal shape under a torsional stress and tending to return to said normal shape.

15. A diaphragm having a conical portion surrounded by a portion formed of a plurality of like torsioned elements Which tend to return to a normal configuration.

16. A diaphragm having a conical portion fixedly attached to and surrounded by a portion formed of a plurality of torsioned radially disposed connected elements.

17. In combinationya conical diaphragm having a conical portion surrounded by a portion formed of like torsioned elements, and flexible means attached to the second named portion for mounting said diaphragm.

18. A diaphragm comprising a peripheral pleated portion oi truncated conical form and a central portion of conical form inverted with respect thereto.

19. A diaphragm comprising a peripheral pleated portion of fixed elements having a truncated conical form and a central ree-ntrant portion of conical form.

20. A diaphragm comprising a pleated peripheral portion having a truncated conical form and a central reentrant portion of conical form.

21. A diaphragm comprising a pleated portion having the form or" a frustum of a cone and a central portion of conical shape secured thereto. 1

22. A diaphragm comprising a peripheral pleated portion of fixed elements having a truncated conical form and a central reentrant portion.

23. A diaphragm comprising a pleated peripheral portion having a truncated conical form and a central reentrant portion.

2a. A diaphragm comprising a peripheral converging portion'and a central portion reentrant With respect to said peripheral portion, one of said portions being pleated.

25. A diaphragm comprising a pleated base portion of conical. form and a pleated center portion fixedly secured thereto.

26. A diaphragm comprising a pleated portion having the form of a trustum of a cone and a pleated substantially planar portion secured to the centerthereof.

27. A diaphragm comprising a peripheral pleated portion of truncated conical form and a central pleated portion.

In testimony whereof I have signed this specification.

WVILLIAM D. LA RUE; 

